Tap changing voltage regulator for single phase three-wire system



E I Aug. 1955 I SHUZO TAKEDA 3,200,325

TAP CHANGING VOLTAGE REGULATOR FOR SINGLE PHASE THREE-WIRE SYSTEM FiledJuly 10, 1962 2 Sheets-Sheet 1 R- 3- INVENTQR.

Aug. 10, 1965 SHUZO TAKEDA 3,200,325 TAP CHANGING VOLTAGE REGULATOR FORSINGLE PHASE THREE-WIRE SYSTEM Filed July 10, 1962 2 Sheets-Sheet 2 55E1 n a [4% I1 I I /0 RS I I i 26 g- 1 I I 1 3 M30 3 :i/4 i 25 2-c *20'INVENTOR.

United States Patent O 3,200,325 TAP CHANGING VOLTAGE REGULATGR PGSINGLE PHASE THREE-WIRE SYSTLM Shuzo Takeda, Yodogawa-ku, Osaka, Japan,assignor to )saka Transformer Co., Ltd, @saha, Osaka Prefecture,

apan

Filed July 10, 1962, Ser. No. 208,836 4 Claims. (Cl. 323-435) Thepresent invention relates to an improved tap changing voltage regulatorfor a single phase three-wire system, and more particularly to animproved tap changing voltage regulator in which the neutral point in asingle phase three-wire system is utilized.

One type of prior art tap changing voltage regulator for a single phasethree-wire system comprises controlling an auto-transformer, -a seriestransformer, a reversing switch, and a selector switch and in the aboveprior art device, output voltage in the secondary coil of said seriestransformer has been regulated by controlling or adjusting the excitingvoltage in the primary coil of said series transformer by means of tapchanging in the selector switch or bymeans of polarity-reversing in saidreversing switch.

In a device according to the present invention, the above mentionedcontrolling auto-transformer is not employed in the single phasethree-wire system.

The object of the present invention is to provide an improved tapchanging voltage regulator for a single phase three wire-system which iscapable of controlling voltage over a wider range with a relativelysimpler construction and reduced cost for manufacture thereof ascompared with prior art devices.

The tap changing voltage regulators of the present invention aremarkedly different from the prior art devices which employ controllingauto-transformers In a tap changing voltage regulator of the presentinvention, two input line terminals which are not at the neutral pointof the single phase three-wire system are respectively connected tostationary contacts at both ends of a selector switch having fivestationary contacts and to the secondary coil of a series transformer.The primary coil of said series transformer is connected to both thecenter stationary contact of the selector switch and the moving contactof a reversing switch which is for changing input line terminals. Andthe neutral terminal in the single phase three-wire system is connectedto both the stationary cont-acts disposed at the opposed sides of theneutral contact. Since the moving contact of the reversing switch can beshifted in a predetermined order in response to the shifting action ofthe moving contact of the selector switch, voltage regulation can beeffected over a wide range in a relatively simple manner.

In a device according to the present invention, since the controllingauto-transformer which has been absolutely necessary in the prior artdevices can be eliminated, the construction of such a voltage regulatordevice can be simplified and made compact, which results in reducedcosts for manufacture of such a device.

In an embodiment of the present invention, the selector switch isprovided with two moving contacts and the center tap of a bridge reactorwhich bridges between these two moving contacts is connected to one endof the primary coil of the series transformer, and the number ofregulation steps for output line voltage can be increased by properarrangement of mutual relations between the moving contact of thereversing switch and the 'ice moving contacts of the selector switch.Furthermore, the primary coil of the series transformer is provided Withseveral taps and these taps are connected through a coarse switch to themoving contact of the reversing switch and by proper arrangement ofmutual relations between the moving contacts of the reversing switch, ofthe selector switch and of the coarse switch, the range of regulationfor output line voltage can be increased as in the former case.

In another embodiment of the present invention, the primary coil of aseries transformer is provided with a center tap and this center tap isconnected through a bridge resistor or bridge reactor and a bridgeswitch to the neutral terminal of the system, thereby the bridge switchcloses just before the moving contact of the selector switch travels toanother stationary contact from the previous one and the same opensimmediately after said moving contact has moved to said anotherstationary contact, whereby to prevent failure due to induced voltagefrom taking place when tap changing operation is being carried out inthe selector switch. In this case, since a bridge resistor or bridgereactor is separated from the movable parts of the selector switch andis connected to the center tap of the primary coil of the seriestransformer, as compared with the prior art arrangement wherein a bridgeresistor or bridge reactor is connected to an auxiliary moving contactof the selector switch, the construction of the selector switch by thepresent invention can be greatly simplified and the same can be formedin a comparatively compact form.

The above and other features and attendant advantages of the presentinvention will become apparent to those skilled in the art from areading of the following detailed explanation of several preferredembodiments thereof in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is an electric circuit diagram of a prior art tap changingvoltage regulator for a single phase threewire system;

FIGS. 25 inclusive show the electric circuit diagrams of severalpreferred embodiments of tap changing voltage regulators according tothe present invention respectively.

Now referring to the figures of the drawings, especially to FIG. 1 inwhich an electric circuit diagram of a prior art tap changing voltageregulator employed for a single phase three-wire system is shown. Asseen from this figure, input line terminals 1 and 2 of the single phasethree-wire system are connected to the respective end terminals of acontrolling auto transformer AT and saidinput line terminals 1 and 2 arefurther connected through the two respective secondary coils 5' and 6 ofa series transformer ST to the respective output terminals 10 and 29.The neutral point of the controlling auto-transformer AT is connected toneutral point terminals 3 and 30. A selector switch SS is provided withstationary contacts 11, 1 2, 13 and 14- and the three stationarycontacts 12, 1'3 and .14- out of these four stationary contacts arerespectively connected to each one tap of the controllingautotransformer. The remaining outermost stationary contact 11 isconnected to a moving contact 7 of a reversing switch RS whosestationary contacts 8 and 9 are connected to the respective input lineterminals 1 and 2 and the contact 1 1 is also connected to one end of aprimary coil 4 of the series transformer ST. The other end of saidprimary coil 4 is connected to a moving contact 16 of the selectorswitch SS. With the above arrangement,

3 by controlling exciting voltage to the primary coil 4 of the seriestransformer ST through tap changing by the selector switch SS orpolarity reversing by means of the reversing switch, output lineterminal voltage of the secondary coils 5 and 6 of the seriestransformer ST can be The following table indicates that in the aboveoperation, depending upon variance in mutual relations between steppositions of the moving contact 7 of the reversing switch RS and stepposit-ions of the moving contact 16 of the selector switch SS, outputline terminal voltage is ad- 11 5 justable in five different ways.

Table 1 Step position I II 'III IV V Position of moving contact 7 ofContact 9 Contact 9 Contact 8 or 9 or Contact 8.... Contact 8.

reversing switch RS. between them. Position of moving contact 16 Contact11.; Contact 12 Contact 13 Contact 14.. Contact 15.

of selector switch SS.

According to the present invention, however, the con- In an embodimentas shown in FIG. 3, one end of the trolling auto-transformer AT as shownin FIG. 1 is eli-miprimary coil 4 of a series transformer ST isconnected nated, and instead of the auto-transformer necessitated in tothe center tap of a bridge reactor 18 connected be the prior art device,as shown in FIG. 2, stationary contween the two moving contacts 16 and17. In this emtacts 8 and 9 of the reversing switch RS are disposed be-20 bodiment, since the moving contacts 16 and 17 can also tween theinput line terminals 1 and 2 which are conoperate '11 a bridgingposition in which these moving nected to the respective secondary coils5 and 6 of the contacts are in contact with their respective adjacentsta- Series transformer ST and to the end stationary contacts t-ionarycontacts .14- and 1 5 of the selector switch SS in a 1 1 and 15 of theselector switch SS, and the center stabridge-over manner, anintermediate voltage can'be o tionary contact 13 of the selector switchSS is connected tained at the output line terminals, said intermediateto the moving contact 7 of the reversing switch RS tovoltage is a valuebetween the two stationary contacts 14 gether with the primary coil 4 ofthe series transformer and 15,'and accordingly, the step number for tapchang- ST, and furthermore, the stationary contacts 12 and 14 ing can befurther increased as compared that in an emdisposed adjacent to bothsides of said centrally disposed bodiment of FIG. 2. stationary contact13 are connected to th ut l li The following table indicates that intheembodiment terminals 3 and 30. i of FIGJ3; depending upon variance inmutual relations And when the moving contact 1 6 of the selector switchbetween the step positions of the moving contact 7 of the SS is shiftedfrom the stationary contact 111 to the stasing switch RS a the ppositions of the moving tionary contact 15, the moving contact 7 of thereversing Contact 1' 0f the Selector Switdh $5, W line tell switch RSoperates as follows in cooperation with the minal voltage is adjustablein nine different y Table 2 Step position I II III IV V VI VII VIII IXPosition of moving con- Contact Contact Contact Contact Contact 9 or 8,Contact Contact Contact Contact tact 7 of reversing 9. 9. 9. 9. orbetween 8. 8. 8. 1 8. switch RS. 7 them. Position of moving con- ContactContact Contact Contact Contact 13 Contact Contact Contact Contact tact16 gig selector 11.- 11. 12. .12. g V, a V .13. 14. 14. 15.

ofrnoving con- Contact Contact, Contact Contact Contact 13. ContactContact Contact Contact tact 17 of selector 11. y 12. 12. .13. 14. a a14. 15. 15. switch SS.

selector switch SS, that is, for instance, when the moving FIG. 4 showsanother embodiment of the present incontact 1 6 of the selector switchS5 is in contact with the vention, and in this embodiment the primarycoil 4 of stationary contact 11 or the stationary contact 12, the theseries transformer ST is provided with several taps moving contact 7 ofthe reversing switch RS comes to and these taps are connectedto therespective stationary contact with the stationary contact9 whilst whenthe m-ovcontacts 21, 22 and 23 of the coarse switch CS. In ing contact1'6 comes to contact with the stationary conthis embodiment, by shiftingthe moving contact 24 of tact :13, the moving contact 7 of the reversingswitch RS thelcoa'rse switch, the step number for top changing can comesto contact with the stationary contact 8 or the stabe increased.ti-onary contact 9, or is in termediately disposed between The followingtable indicates that in the embodiment the two stationary contacts 8and9, as shown in FIG. 4, dependingupon mutual relations And when themoving contact 1 6 of the selector switch among step positions of themoving contact 7 of the recomes to contact with the stationary contact14 or the versing switch RS, step positions of the moving contactstationary contact 15, the moving contact 7 of the revers- 16 of theselector switch SS and step positions of the movm-g switch RS comes tocontact with the stationary coning contact 24 of the coarse switch CS,output line tertact 8. rninal voltage is adjustable in nine differentways.

Table 3 1 Step position I II III 1V V VI v11 7 VIII IX Position ofmoving con- 'Contact Contact Contact Contact Contact9or 8, ContactContact Contact Contact iiggflofreversmgswitch 9. 9. 9. 9. of} between8. 8. s 8. 8. Position of moving con- Contact Contact Contact ContactConi t 13. 7 Contact Contact Contact Contact gzgrt 16 of selector switch11. 11. 11. 12. 14. 15. 15. 115. Position of moving con- Contact ContactContact Contact Contact 21. Contact Contact Contact Contact iigt 24 ofcoarse switch 23. 22. 21. 21. 21. 21. 22. 23.

FIG. 5 shows another embodiment of the present invention and in thisembodiment, the primary coil 4 of the series transformer ST is providedwith a center tap 25 and this center tap 25 is connected through abridge resistor or bridge reactor 26 and a bridge switch 27 to a neutralterminal 34 thereby to prevent any failure due to induced voltage takingplace in case of tap changing.

In this embodiment, mutual relations between step positions of themoving contact 7 of the reversing switch RS and step positions of themoving contact 16 of the selector switch SS are exactly the same as inthe embodiment of FIG. 2 and the output line terminal voltage isadjustable in five different ways. However, in the embodiment of FIG. 5,the bridge switch 27 closes just before the moving contact 16 of theselector switch SS travels to another stationary contact from theprevious one, and opens immediately after the moving contact has justarrived at said another contact position. In this way, the bridge switch27 and the moving contact 16 of the selector switch SS are mechanicallyrelated to each other in their operations.

It will be understood that modifications and variations on theembodiments of the invention as disclosed herein may be resorted toWithout departing from the scope of the concept of the presentinvention. Therefore the scope of the invention should be limited onlyby the scope and proper interpretation of the claims appended hereto.

What I claim is:

1. A tap changing voltage regulator for a single phase three-wire systemcomprising, in combination, first and second input line terminals and aneutral line terminal, a selector switch having first, second, third,fourth and fifth contacts, a series transformer having first and secondsecondary coils and a primary coil, each of said secondary coils havingan input conductor and an output terminal, first and second inputconductors associated with said primary coil, a reversing switch havingfirst, second and third terminals and a movable contact selectivelyinterconnecting said third terminal to said first or said secondreversing switch terminal, conductors interconnecting said first inputline terminal with said first reversing switch terminal, said firstselector switch contact and the input conductor of said first secondarycoil, conductors interconnecting said second input line terminal withsaid second reversing switch terminal, said fifth selector switchcontact and the input conductor of said second secondary coil, a thirdoutput terminal, conductors interconnecting said neutral line terminalto said second and fourth selector switch contacts and said third outputterminal, a conductor interconnecting said reversing switch thirdterminal with said selector switch third contact, said primary coilfirst input conductor being connected with said reversing switch thirdterminal, said selector switch including movable contact means connectedto said primary coil second input conductor selectively connecting saidprimary coil second input conductor with at least one of said first,second, fourth or fifth selector switch contacts.

2. In a tap changing voltage regulator for a single phase three-wiresystem as in claim 1, a bridge reactor having first and secondconductors and a center tap, said primary coil second input conductorbeing connected to said center tap and said bridge reactor first andsecond conductors being connected to said selector switch movablecontact means and being connectible to two of said selector switchfirst, second, third and fourth contacts.

3. In a tap changing voltage regulator for a single phase three-wiresystem as in claim 1, wherein said primary coil includes a plurality oftaps and said primary coil first input conductor is selectivelyconnected to one of said taps.

4. In a tap changing voltage regulator for a single phase three-wiresystem as in claim 1, wherein said primary coil includes a center tap, abridge resistor having an input connected to said primary coil centertap and an output conductor, a bridge switch having a first terminalconnected to said bridge resistor output conductor and a second terminalconnected to said third output terminal and means interconnecting saidbridge switch and said selector switch movable contact means wherebysaid bridge switch closes immediately prior to movement of said selectorswitch movable contact means and opens immediately after movement ofsaid selector switch movable contact means ceases.

Reterences Cited by the Examiner UNITED STATES PATENTS- 2,036,305 4/36Snyder 323-47 X 2,063,693 12/36 McCarty 323-45 2,770,767 11/56 Nelson323-45 X LLOYD MCCOLLUM, Primary Examiner. ROBERT L. SIMS, Examiner.

1. A TAP CHANGING VOLTAGE REGULATOR FOR A SINGLE PHASE THREE-WIRE SYSTEMCOMPRISING, IN COMBINATION, FIRST AND SECOND INPUT LINE TERMINALS ANDANEUTRAL LINE TERMINAL, A SELECTOR SWITCH HAVING FIRST, SECOND, THIRD,FOURTH AND FIFTH CONTACTS, A SERIES TRANSFORMER HAVING FIRST AND SECONDSECONDARY COILS AND A PRIMARY CLIL, EACH OF SAID SECONDARY COILS HAVINGAN INPUT CONDUCTOR AND AN OUTPUT TERMINAL, FIRST AND SECOND INPUTCONDUCTORS ASSOCIATED WITH SAID PRIMARY COIL, A REVERSING SWITCH HAVINGFIRST, SECOND AND THIRD THERMINALS AND A MOVABLE CONTACT SELECTIVELYINTERCONNECTING SAID THIRD TERMINAL TO SAID FIRST OR SAID SECONDREVERSING SWITCH TERMINAL, CONDUCTORS INTERCONNECTING SAID FIRST INPUTLINE TERMINAL WITH SAID FIRST REVERSING SWITCH TERMINAL, SAID FIRSTSELECTOR SWITCH CONTACT AND THE INPUT CONDCUTOR OF SAID FIRST SECONDARYCOIL, CONDUCTORS INTERCONNECTING SAID SECOND INPUT LINE TERMINAL WITHSAID SECOND REVERSING SWITCH TERMINAL, SAID FIFTH SELECTOR SWITCHCONTACT AND THE INPUT CONDUCTOR OF SAID SECONDARY SECONDARY COIL, ATHIRD OUTPUT TERMINAL, CONDUCTORS INTERCONNECTING SAID NEUTRAL LINETERMINAL TO SAID SECOND AND FOURTH SELECTOR SWITCH CONTACTS AND SAIDTHIRD OUTPUT TERMINAL, A CONDUCTOR INTERCONNECTING SAID REVERSING SWITCHTHIRD TERMINAL WITH SAID SELECTOR SWITCH THIRD CONTACT, SAID PRIMARYCOIL FIRST INPUT CONDUCTOR BEING CONNECTED WITH SAID REVERSING SWITCHTHIRD TERMINAL, SAID SELECTOR SWITCH INCLUDING MOVABLE CONTACT MEANSCONNECTED TO SAID PRIMARY COIL SECOND INPUT CONDCUTOR SELECTIVELYCONNECTING SAID PRIMARY COIL SECOND INPUT CONDUCTOR WITH AT LEAST ONE OFSAID FIRST, SECOND, FOURTH OR FIFTH SELECTOR SWITCH CONTACTS.